Assessment of Upper Cretaceous Strata for Offshore CO2 Storage, Southeastern United States

Khaled F. Almutairi, Camelia C. Knapp, James H. Knapp, and Darrell A. Terry

School of the Earth, Ocean, and Environment, University of South Carolina, Columbia, SC 29208, USA

Abstract: This is the first assessment ofUpper Cretaceous strata for offshore CO2 storage resources in the southeastern United States outer continental shelf. This study focuses on Upper Cretaceous geological units using legacy industry 2-D seismic reflection and well data. Itprovides an integrated description, and reliable subsurface evaluation of Upper Cretaceous potential storage reservoirs.Structure and thickness (isochore) maps were generated for the main potential reservoirs and seals. Results indicate that Upper Cretaceous geologic units consist of moderately to highly compartmentalized stratigraphic systems. Five reservoirs and seals were recognized as potential storage units. Two reservoirs are particularlyconsidered as the main CO2 storage units with quality and integrity capableto meet the CO2 storage requirements by the U.S. Department of Energy. They consist of limestone deposits with significant interbedded sandstones, shales and dolomites, and are sealed by thick shales interbedded with limestone. The porosity ranges from 20 to 30% and the permeability ranges from 1 to 447 mD. Regional CO2 storage capacity is estimated to be approximately 32 GT in Upper Cretaceous units. The local storage capacity for the two significant reservoirs in the Southeast Georgia Embayment contribute ~ 9 GT of that

amount.

Key words: Atlantic offshore, Southeast Georgia Embayment, CO2 Sequestration, Geologic Storage, Upper Cretaceous